I really hated the Slugger, I found that fully upgraded it was way worse than a stock JT for its tier. No camo, poor mobility, (IMO, despite what people say) weak gun, bad armor layout, weak to HE, etc. The only redeeming quality is the rapid fire gun which is good for kill stealing and getting confederate.

The T25 on the other hand is a ton of fun once you get some upgrades. Just make sure to get the engine through the Pershing first so you only have to worry about getting the gun. The raw mobility of the T25 makes up for the weak 90mm. It'll be an amazing med support tank once you get the 105.